Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share [Abstract]
Net income before attribution of noncontrolling interest	$ 21,741			$ 17,490			$ 48,729	$ 40,145
Noncontrolling interest	(378)	$ (262)	$ (244)	(44)	$ (72)	$ (1,076)	(884)	(1,192)
Net income attributable to Amerant Bancorp Inc.	$ 22,119	$ 7,308	$ 20,186	$ 17,534	$ 8,424	$ 15,379	$ 49,613	$ 41,337
Basic weighted average shares outstanding (in shares)	33,489,560			33,476,418			33,537,759	33,985,856
Dilutive effect of share-based compensation awards (in shares)	207,060			270,460			218,756	267,706
Diluted weighted average shares outstanding (in shares)	33,696,620			33,746,878			33,756,515	34,253,562
Basic earnings per common share (in dollars per share)	$ 0.66			$ 0.52			$ 1.48	$ 1.22
Diluted earnings per common share (in dollars per share)	$ 0.66			$ 0.52			$ 1.47	$ 1.21
Non-vested shares (in shares)	577,511			532,867			577,511	532,867